Here's what we know about Nikolas Cruz, the suspected 19-year-old gunman in the Florida high school shooting

Nineteen-year-old Nikolas Cruz has been identified as the suspect in the high school shooting that killed at least 17 people on Wednesday.

Cruz was previously expelled from the high school and was described as "quiet and strange" by his peers.

Comments and photos on social media accounts believed to have belonged to Cruz revealed threats and several firearms.

Nineteen-year-old Nikolas Cruz has been identified as the suspect in the shooting that killed at least 17 people at the Marjory Stoneman Douglas High School in Parkland, Florida on Wednesday.

Cruz was reportedly armed with an AR-15-styled semiautomatic rifle and "countless magazines," the Broward Sheriff's Office said. Law enforcement officials familiar with the shooting said Cruz also possessed a gas mask and smoke grenades, Sen. Bill Nelson of Florida said on CNN.

Cruz was believed to have intentionally set off the school's fire alarms "so the kids would come pouring out of the classrooms into the hall," during the shooting, Nelson continued.

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Shooting at Marjory Stoneman Douglas High School in Florida

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Shooting at Marjory Stoneman Douglas High School in Florida

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

PARKLAND, FL - FEBRUARY 14: People wait for loved ones as they are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students leave Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting. A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Eva Claire HAMBACH (Photo credit should read EVA CLAIRE HAMBACH/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students are released from a lockdown outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

Medical personnel tend to a victim outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

Medical personnel tend to a victim outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

Police and security vehicles are seen at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting. A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve SANDBERG / The erroneous mention[s] appearing in the metadata of this photo by Michele Eve SANDBERG has been modified in AFP systems in the following manner: [Byline: Michele Eve SANDBERG] instead of [Eva Hambach]. Please immediately remove the erroneous mention from all your online services and delete it from your servers. If you have been authorized by AFP to distribute it to third parties, please ensure that the same actions are carried out by them. Failure to promptly comply with these instructions will entail liability on your part for any continued or post notification usage. Therefore we thank you very much for all your attention and prompt action. We are sorry for the inconvenience this notification may cause and remain at your disposal for any further information you may require. (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Students react following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018. A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: The Marjory Stoneman Douglas High School is seen after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Security speak with people near Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting. A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michelle Eve SANDBERG (Photo credit should read MICHELLE EVE SANDBERG/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students gather following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami, February 14, 2018 . A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

A student wears a Valentine's pin as she leaves Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting. A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help. The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: Fire Rescue personnel work the scene at the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students leave Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Parents confer with security following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami, February 14, 2018 .
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Police officers ride in the back of a pick up truck with a victim outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

A law enforcement officer directs traffic outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

A young woman who just walked out from the direction of the high school, who refused to give her name, gets a hug as she reaches the overpass at Coral Springs Drive and the Sawgrass Expressway just south of the campus of Marjorie Stonemason Douglas High School where a shooting occurred on Wednesday, Feb. 14, 2018 in Parkland, Fla. (Amy Beth Bennett/Sun Sentinel/TNS via Getty Images)

A student reacts as she talks to a television reporter at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Students react at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

People react at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018 following a school shooting.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students are released from a lockdown outside of Stoneman Douglas High School in Parkland, Fla. after reports of an active shooter on Wednesday, Feb. 14, 2018. (John McCall/Sun Sentinel/TNS via Getty Images)

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students are evacuated by police out of Stoneman Douglas High School in Parkland, Fla., after a shooting on Wednesday, Feb. 14, 2018. (Mike Stocker/Sun Sentinel/TNS via Getty Images)

PARKLAND, FL - FEBRUARY 14: People are brought out of the Marjory Stoneman Douglas High School after a shooting at the school that reportedly killed and injured multiple people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

Students react following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Students react following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Students react following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018.
A gunman opened fire at the Florida high school, an incident that officials said caused 'numerous fatalities' and left terrified students huddled in their classrooms, texting friends and family for help.
The Broward County Sheriff's Office said a suspect was in custody. / AFP PHOTO / Michele Eve Sandberg (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Students are brought across Coral Springs Drive from the campus of Stoneman Douglas High School in Parkland, Fla., after a shooting on Wednesday, Feb. 14, 2018. (Amy Beth Bennett/Sun Sentinel/TNS via Getty Images)

Waiting for word from students at Coral Springs Drive and the Sawgrass Expressway just south of the campus of Stoneman Douglas High School in Parkland, Fla., after a shooting on Wednesday, Feb. 14, 2018. (Amy Beth Bennett/Sun Sentinel/TNS via Getty Images)

Waiting for word from students at Coral Springs Drive and the Sawgrass Expressway just south of the campus of Stoneman Douglas High School in Parkland, Fla., after a shooting on Wednesday, Feb. 14, 2018. (Amy Beth Bennett/Sun Sentinel/TNS via Getty Images)

Trauma surgeon Dr. Igor Nichiporenko (C) and director for emergency medicine Dr. Evan Boyar (R) address the media outside the Broward Health Emergency facility where victims were taken following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, a city about 50 miles (80 kilometers) north of Miami on February 14, 2018.
Seventeen people were killed when a 19-year-old former student opened fire with a semi-automatic rifle at the Florida high school, the local sheriff said, calling the scene 'horrific.' Broward County Sheriff Steve Israel said the victims were a mix of students and adults, though he could not confirm if the adults were teachers. / AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Waiting for word from students at Coral Springs Drive and the Sawgrass Expressway just south of the campus of Stoneman Douglas High School in Parkland, Fla., after a shooting on Wednesday, Feb. 14, 2018. (Amy Beth Bennett/Sun Sentinel/TNS via Getty Images)

Florida Governor Rick Scott (4th-L) visits Marjory Stoneman Douglas High School following a shooting that killed 17 people on February 14, 2018 in Parkland, Florida.
A former student armed with an AR-15 rifle opened fire at a Florida high school, killing at least 17 people, officials said, in a harrowing shooting spree that saw terrified students hiding in closets and under desks as they texted for help. Broward County Sheriff Scott Israel identified the gunman as Nikolas Cruz, 19, a former student at Marjory Stoneman Douglas High School in Parkland who had been expelled for 'disciplinary reasons.'
/ AFP PHOTO / Gaston De Cardenas (Photo credit should read GASTON DE CARDENAS/AFP/Getty Images)

BROWARD, UNITED STATES - FEBRUARY 14: Students meet their families following a school shooting at Marjory Stoneman Douglas High School in Broward, Florida on February 14, 2018. At least 17 people were killed Wednesday when a lone gunman opened fire on a Florida high school, according to police. The victims are a mix of students and adults, officials said. (Photo by Carlos Miller/Anadolu Agency/Getty Images)

Police vehicles block the road to Marjory Stoneman Douglas High School in Parkland, Florida, following a shooting that killed 17 people on February 14, 2018 in Parkland, Florida.
A former student armed with an AR-15 rifle opened fire at a Florida high school, killing at least 17 people, officials said, in a harrowing shooting spree that saw terrified students hiding in closets and under desks as they texted for help. Broward County Sheriff Scott Israel identified the gunman as Nikolas Cruz, 19, a former student at Marjory Stoneman Douglas High School in Parkland who had been expelled for 'disciplinary reasons.'
/ AFP PHOTO / Gaston De Cardenas (Photo credit should read GASTON DE CARDENAS/AFP/Getty Images)

PARKLAND, FL - FEBRUARY 14: Nathanael Clark (L) and his father, John Clark, speak to the media after Nathanael escaped the shooting at Marjory Stoneman Douglas High School that killed 17 people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

PARKLAND, FL - FEBRUARY 14: Sarah Crescitelli leans on her mother, Stacy Crescitelli (L) after she escaped the shooting at Marjory Stoneman Douglas High School that killed 17 people on February 14, 2018 in Parkland, Florida. Numerous law enforcement officials continue to investigate the scene. (Photo by Joe Raedle/Getty Images)

The location where suspect Nikolas Cruz was caught by police at a townhouse in Pelican Pointe at Wyndham Lakes in Coral Cables, Florida following the deadly shooting at Marjory Stoneman Douglas High School in Parkland, Florida on Febreuary 14, 2018.
A former student armed with an AR-15 rifle opened fire at a Florida high school, killing at least 17 people, officials said, in a harrowing shooting spree that saw terrified students hiding in closets and under desks as they texted for help. Broward County Sheriff Scott Israel identified the gunman as Nikolas Cruz, 19, a former student at Marjory Stoneman Douglas High School in Parkland who had been expelled for 'disciplinary reasons.'
/ AFP PHOTO / Michele Eve SANDBERG (Photo credit should read MICHELE EVE SANDBERG/AFP/Getty Images)

Parents meet at the Fort Lauderdale Marriott Coral Springs Hotel to pick up their children following a mass shooting at nearby Marjory Stoneman Douglas High School in Parkland, Fla., on Wednesday, Feb. 14, 2018. (Jim Rassol/Sun Sentinel/TNS via Getty Images)

Parents meet at the Fort Lauderdale Marriott Coral Springs Hotel to pick up their children following a mass shooting at nearby Marjory Stoneman Douglas High School in Parkland, Fla., on Wednesday, Feb. 14, 2018. (Jim Rassol/Sun Sentinel/TNS via Getty Images)

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Following the height of the shooting, Cruz reportedly tried to escape by blending in with other fleeing students, law enforcement sources and eyewitnesses told ABC News. Though he managed to leave the school, he was later apprehended after the police identified him through surveillance videos, CNN correspondent Martin Savidge reported.

Cruz, who was detained without incident and was transported to the hospital for labored breathing, has been the only suspect named in the shooting, according to Savidge.

Kicked out of high school

Though investigators are still looking at motives for the shooting, details on Cruz's life have begun to emerge from fellow students and investigators.

Cruz was reportedly expelled from Marjory Stoneman Douglas for disciplinary reasons, according to multiple news reports. Though school officials did not confirm the exact reason for Cruz's expulsion, a 17-year-old junior said he was expelled after a fight with his ex-girlfriend's new boyfriend, the Associated Press reported.

Jim Gard, one of Cruz's former teachers, said that he was told Cruz "wasn't allowed on campus with a backpack on him," The Miami Herald reported.

A student who attended the same alternative high school as Cruz said that he was known to have flaunted pictures of firearms on his phone.

"He shot guns because he felt that it gave him an exhilarating feeling," the student said on WSVN-7 News. "He showed me personally through his phone."

"I didn't want to cause any conflict with him because that's the impression he gave off," the student continued.

The student also said that he knew Cruz had guns at his home for two years.

"It surprises me the fact that this is going on today, but it doesn't shock me that it was him," the student continued. "It was an eye-opener."

Another student who was assigned to a school project with Cruz said he had aspirations to join the military and enjoyed hunting, CNN reported.

"He always just seemed very quiet and strange," the student said. "Just always to himself, never really tried to associate with anybody, but once given the opportunity, he liked to talk."

Cruz's mother, Lynda Cruz, reportedly had trouble with his behavior in the past. Lynda would occasionally contact the police to give him behavioral advice at their home, according to Helen Pasciolla, a former neighbor.

"I think she wanted to scare them a little bit," Ms. Pasciolla said. "Nikolas has behavioral problems, I think, but I never thought he would be violent," Pasciolla said in The New York Times.

Threatening comments on social media

Cruz is also believed to have posted images of his guns and made threats on social media accounts.

He allegedly commented nine months ago that he was going to kill law enforcement officials "one day" because they "go after the good people," CNN investigative correspondent Drew Griffin said.

Another comment by Cruz reportedly said he wished "to kill as many as I can," Griffin reported.

Several pictures posted on an Instagram account believed to belong to Cruz revealed firearms, ammunition, and accessories, such as scopes, The Times reported.

Other images from the alleged Instagram account contained pictures of shooting practice sheets and a man wearing a hat imprinted with US Army's logo.

Broward County sheriff Scott Israel, who has reportedly begun learning about Cruz's social media presence, called it "very, very concerning," The Times continued.